The present invention relates to training and rehabilitating brain function, and in particular, to the use of hemi-lens to accomplish this purpose.
Brain injury, such as Cerebral Vascular Accident (stroke), closed head injury, penetrating head wounds, and invasive growths can generate a variety of sensory/perceptual and other cognitive disturbances that significantly impact the ability of individuals to maintain independence in their environments. When this insult occurs in the posterior regions of the brain, especially the parietal and/or occipital lobes, a change in the functioning of the visual perceptual system can occur. These sensory/perceptual disturbances involve inattention to visual stimuli to a varying degree, from mild inattention to details to complete loss of recognition of visual information in a given visual field. In some instances, perception of the visual field disappears completely.
Rehabilitation of the patient with a visual perceptual defect is limited. Most techniques involve behavioral and/or cognitive training directed at focused extra attention to the visual field that has been disrupted. The results of this type of rehabilitation have been successful, but limited.
Recent evidence showing that attention plays an essential role in almost all other brain functions including motor functioning in stroke patients with hemiparesis or hemiplegia, suggests that any technique that can improve attention related to brain injury might help in the recovery of many non-vision related brain functions. In addition, some research has established a relationship between hemispheric attention and visual processing in the dysfunction of developmental reading disorder, the most common type of learning disability.
Furthermore such improvement in brain function could also be effective in visual training in non-medical settings. For example, baseball batters use asymmetric visual information when standing at the plate judging pitches. Isolating the field that captures the pitcher and pitch, and blocks the catcher, umpire, and other distractions might significantly improve batting performance.
Contact lens, glasses and the like are known in which areas of the lens are rendered opaque or semi-opaque for the purpose of correcting defects in vision or to shield the eye from damage.
Harrell, E. H., T. Kramer-Stutts, and A. J. Zolten, "Performance of Subjects with Left Visual Neglect after Removal of the Right Visual Field Using Hemifield Goggles," Journal of Rehabilitation, (October/November/December 1995), pp. 46-49, discloses improved performance with visual input directed to a neglected field when the non-neglected field is occluded. Harrell et al. disclose complete occlusion of the visual field directed to one hemisphere of the brain.
Harrell et al. disclose changing the amount of visual field input by adjusting the Velcro strips which provide the occlusion over the goggles used in the experiment described in the article. Harrell et al. do not, however, disclose the use of a series of lenses of varying degrees of opacity, such as semi-opaque areas, in the course of visual retraining.
While Harrell et al. suggest that in the future a procedure using contact lenses might be preferable to goggles, they conclude that this would be expensive and probably not feasible for practical applications in rehabilitation.
One of the problems in using contact lens having occluded areas is that the contact lens must sit on the eye without rotation. Various techniques are known for maintaining the position of a contact lens without rotation. For example, such techniques are disclosed in U.S. Pat. Nos. 4,324,461; 5,483,304; 5,502,518; and 5,570,142. Also, various techniques are known for manufacturing contact lenses with opaque areas.